Xu Zhen, Chen Xue, Zhi Huiying, Gao Juan, Bialkowska Katarzyna, Byzova Tatiana V, Pluskota Elzbieta, White Gilbert C, Liu Junling, Plow Edward F, Ma Yan-Qing
From the Collaborative Research Program for Cell Adhesion Molecules, Shanghai University School of Life Sciences, Shanghai, China (Z.X., J.G., E.F.P., Y.-Q.M.); Blood Research Institute, Blood Center of Wisconsin, Milwaukee (Z.X., H.Z., G.C.W., Y.-Q.M.); Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao-Tong University School of Medicine, Shanghai, China (X.C., J.L.); and Department of Molecular Cardiology, Cleveland Clinic, OH (K.B., T.V.B., E.P., E.F.P.).
Arterioscler Thromb Vasc Biol. 2014 Sep;34(9):1961-7. doi: 10.1161/ATVBAHA.114.303851. Epub 2014 Jun 26.
Kindlin-3 is a critical supporter of integrin function in platelets. Lack of expression of kindlin-3 protein in patients impairs integrin αIIbβ3-mediated platelet aggregation. Although kindlin-3 has been categorized as an integrin-binding partner, the functional significance of the direct interaction of kindlin-3 with integrin αIIbβ3 in platelets has not been established. Here, we evaluated the significance of the binding of kindlin-3 to integrin αIIbβ3 in platelets in supporting integrin αIIbβ3-mediated platelet functions.
We generated a strain of kindlin-3 knockin (K3KI) mice that express a kindlin-3 mutant that carries an integrin-interaction defective substitution. K3KI mice could survive normally and express integrin αIIbβ3 on platelets similar to their wild-type counterparts. Functional analysis revealed that K3KI mice exhibited defective platelet function, including impaired integrin αIIbβ3 activation, suppressed platelet spreading and platelet aggregation, prolonged tail bleeding time, and absence of platelet-mediated clot retraction. In addition, whole blood drawn from K3KI mice showed resistance to in vitro thrombus formation and, as a consequence, K3KI mice were protected from in vivo arterial thrombosis.
These observations demonstrate that the direct binding of kindlin-3 to integrin αIIbβ3 is involved in supporting integrin αIIbβ3 activation and integrin αIIbβ3-dependent responses of platelets and consequently contributes significantly to arterial thrombus formation.
Kindlin-3是血小板中整合素功能的关键支持者。患者中Kindlin-3蛋白表达缺失会损害整合素αIIbβ3介导的血小板聚集。尽管Kindlin-3已被归类为整合素结合伴侣，但Kindlin-3与血小板中整合素αIIbβ3直接相互作用的功能意义尚未明确。在此，我们评估了血小板中Kindlin-3与整合素αIIbβ3结合在支持整合素αIIbβ3介导的血小板功能中的意义。
我们构建了一种Kindlin-3基因敲入（K3KI）小鼠品系，该小鼠表达一种携带整合素相互作用缺陷替代的Kindlin-3突变体。K3KI小鼠能够正常存活，并且血小板上整合素αIIbβ3的表达与野生型小鼠相似。功能分析显示，K3KI小鼠表现出血小板功能缺陷，包括整合素αIIbβ3激活受损、血小板铺展和血小板聚集受抑制、尾部出血时间延长以及血小板介导的血块回缩缺失。此外，从K3KI小鼠采集的全血显示出对体外血栓形成的抗性，因此，K3KI小鼠对体内动脉血栓形成具有保护作用。
这些观察结果表明，Kindlin-3与整合素αIIbβ3的直接结合参与支持整合素αIIbβ3的激活以及血小板的整合素αIIbβ3依赖性反应，从而对动脉血栓形成有显著贡献。
